Remove the skin from the chicken legs and thighs and chop the thighs in half through the bone.
Combine the chicken with the yoghurt and allow to marinate until you are ready to use, or up to 12 hours.
Wash the rice well in cold water, three times until the water comes out clean. Allow it to soak in 1 litre of water for 30 mins.
In a dry skillet, toast the cumin seeds, coriander seeds, cloves, fennel seeds, black peppercorns and cardamom. Toast for 1 min until fragrant and blitz in a spice grinder. If you haven't got a spice grinder, pound the mixture in a mortar and pestle until it forms a fine paste.
Finely slice the onions and finely chop the tomatoes. Thinly slice 1 lemon and chop the last one in half.
Heat up 50ml of oil in a pan and fry the onions until very crispy and darkened. Remove ¼ of the onions and set aside.
Add in the biryani spice mix along with your chilli powder, ½ tsp turmeric, ground nutmeg, cinnamon stick, black cardamom and 2 tsp salt. Cook for 1 min, allowing the spices to bloom and become fragrant.
Add the tomatoes, whole green chillies, sugar, grate in the garlic and ginger. Cook for 5 mins until the tomatoes have softened and are bubbling.
Add in the chicken, yoghurt and 100ml of water. Mix well and cook for 10 mins until the chicken is 80% cooked through. Set aside.
Drain the rice, and cook in 1 litre of fresh cold water with 1 tbsp of ghee, 1 tsp salt, and the juice of half a lemon. Bring to a boil and then set a timer for 4 mins. Drain the par-cooked rice in a sieve and set aside.
Finely chop the coriander and mint. In a small bowl combine 1 tsp turmeric with 4 tbsp milk.
Spread the ghee or butter on the bottom of your heavy-bottomed pan. Spread over half the rice, and top with the cooked chicken and your curried sauce. Make a layer with half of your thinly sliced lemon and then cover it with rice. Top with more rice, mint, coriander, reserved onions. Sprinkle on the turmeric milk mixture to add some colour to the rice.
Cover with a lid and place on a medium heat until you can see steam coming out, then time for 5 mins.
Uncover, plate up with a squeeze of lemon and enjoy.